Vacuum roasting inhibited the diffusion of aluminum in muscovite impurities into quartz during roasting process

Abstract

Existing research on removing metal impurities from quartz mainly focuses on enhancing the exposure and the reactivity of mineral impurities. However, the influence of the mineral impurities on the quartz structure during roasting is not considered. In this study, the influence of muscovite impurities on the quartz structure during roasting was studied using theoretical analysis and cell parameter comparison. It was found that aluminum (Al) in muscovite diffused into the quartz during roasting and forming lattice impurities, hindering the purification of quartz. Arrhenius equation and quartz-muscovite diffusion couple experiments were employed to investigate the method of inhibiting diffusion. And it was concluded that reducing the H₂O content in quartz can effectively inhibit the diffusion behavior of Al. Based on the above research, vacuum roasting process was introduced to enhance the removal of H₂O in quartz. The experimental results shown that under the same conditions, vacuum roasting reduced the H₂O content in quartz from 165.9 μg·g⁻¹ to 37.8 μg·g⁻¹. This led to the reduction of the diffusion distance of Al from 15.8 μm to 6.1 μm. Finally, through data analysis, the functional relationship between water concentration and Al diffusion coefficient in roasting process is $\text{D}={\text{D}}_{\text{0}}{\text{C}}_{{\text{H}}_{\text{2}}\text{O}}^{\text{1.310}}\text{exp}\left(-\frac{\Delta \text{H}}{\text{RT}}\right)$. This study clarifies the influence of mineral impurities on the structure of quartz during roasting, which provides a new solution for the purification of quartz and a reference for optimizing the purification process of quartz and other minerals.